Germany's foreign minister on Wednesday said parliament would likely vote on withdrawing troops involved in the fight against Daesh in Syria from a Turkish military base if Ankara persisted in denying German lawmakers access to the site.

Turkish officials have told Reuters a visit by German lawmakers to some 250 German troops stationed at Incirlik to provide logistical support to the US-led coalition would not be appropriate at the moment.

The deepening row has further soured relations that became increasingly strained ahead of a constitutional referendum in Turkey that handed President Tayyip Erdogan sweeping new powers.

"I can only hope that the Turkish government changes its mind in the coming days. Otherwise, the German parliament will certainly not leave the soldiers in Turkey," Foreign Minister Sigmar Gabriel told the Neue Osnabruecker Zeitung.

Gabriel's comments struck a tough tone after Chancellor Angela Merkel on Tuesday said that Berlin might move the troops elsewhere.

Spiegel Online has reported that Germany was exploring the possibility of redeploying the soldiers to Jordan. The Berliner Zeitung reported that the opposition Greens and Left parties were calling for a vote on pulling the soldiers out.

Relations between the two countries have deteriorated sharply after a series of diplomatic rows.

Turkey was angered by Germany's cancelation of political rallies in support of Erdogan ahead of the Turkish referendum and is furious that Germany is granting asylum to Turks accused of participating in a failed coup last July.

The failed putsch prompted a purge of the Turkish military, judiciary and civil service. German officials have said more than 400 Turkish citizens with diplomatic passports and other government work permits had sought asylum in Germany since then.

Mass-selling daily Bild reported that two Turkish generals had sought asylum at Frankfurt Airport late on Tuesday.

It said the two generals would be taken to a migrant center in Giessen, near Frankfurt, after spending the night near the airport. German police and the Office for Migrants and Refugees declined to comment.